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GUI (Graphical User Interface): A user interface that uses a mouse and a bit-mapped
graphics display to make basic computer operations substantially easier for the
user. Standard features include message boxes, a clipboard, dialog boxes,
scroll boxes, WYSIWYG (what-you-see-is-what-you-get) on-screen page
presentation and multiple on-screen windows.
H
half duplex: A type of data transmission in which data flows between two devices in one
direction at a time. See also full duplex.
handles: Eight small boxes that appear around a graphical object when you select it. You
can use the handles to change the size and shape of the object. Dragging the
middle handle on one side of an object stretches or shrinks the object in that
direction, changing its shape as well as its size. Dragging a corner handle
makes the object larger or smaller while preserving its shape.
hard disk: A storage device composed of a rigid platter or platters that store information
magnetically. Hard disks hold much more information than diskettes and are
used for the long-term storage of programs and data. The primary (or only)
hard disk in a personal computer is usually fixed, but some computers have
secondary hard disks that are removable. In a server, all hard disks may be
removable. By default, the primary hard disk is referred to as drive C.
hardware: The physical, electronic and mechanical components of a computer system,
including devices such as a screen, disk drive, printer, mouse and processor.
hexadecimal: The base-16 numbering system used by programmers to represent binary
numbers. Digits above 9 are represented by letters (the 15 digits are 1, 2, 3, 4,
5, 6, 7, 8, 9, A, B, C, D, E and F). Two hexadecimal digits are equivalent to the
eight bits in a byte. For example, F1 in hexadecimal is equivalent to 11110001
in binary. See also binary, decimal.
high-density diskette: A diskette that holds 1.2 MB (5.25-inch) or 1.44 MB (3.5-inch) of
information.
hot-swappable drives: Drives that you can install or remove without using screws or
cables and without powering down the server.
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